The present invention generally relates to combines and more particularly to an articulated (jointed) combine which employs, inter alia, an improved joint, unloading capability and control, steering, and extremely large grain storage capacity.
A modern agricultural combine typically unloads or transfers clean grain from its on-board storage hopper utilizing an auger of fixed length which swings out in a fixed radius and fixed elevation arc from its stowed position. The stowed position generally is pointing to the rear of the combine. The auger in turn generally is driven by a mechanical arrangement of belts, chains, clutch, and gearbox. The unload auger in most combine designs swings out to the operator's left. The auger length generally is limited by the practical distance that it can extend beyond the rear of the combine in its stowed position without creating a serious maneuvering hazard.
As the size of on-board storage hoppers and capacity of combines has increased, the time required to maneuver the machine next to the grain receiving wagon or truck and the grain transfer time have become a major component of the total harvesting time. Conventional combines have a grain hopper capacity of 250 to 300 bushels and unload auger capacities of 1.9 to 2.6 bushels per second.
The unload time of the hopper typically is about 2 to 3 minutes with the unload auger running at maximum speed and 1 to 2 minutes are taken to maneuver the combine into the optimum unload position next to the truck or wagon. Re-positioning the combine and running the auger at less than maximum speed are often encountered when topping off the truck or wagon which is receiving the grain. As modem combine harvesting capacities approach 3,000 bushes per hour, the unload cycle must be repeated every 8 to 10 minutes. Therefore, the total unload time or non-harvesting time is a significant reduction of total grain harvesting productivity.
This productivity loss can be countered by a second operator utilizing a tractor and grain cart following the combine back and forth through the field to unload the on-board combine storage hopper without stopping the harvesting process. Alternatively, a combine with an integrated grain cart, as disclosed in application Ser. No. 08/927872, cited above, can be utilized to reduce the number of unload cycles and at least double the rate at which grain is discharged to the receiving vehicle.
Unloading combines into semi-trailer road trucks has become the prevalent practice as opposed to field wagons which were utilized in the past. These road trucks typically are parked at the side of the road and not in the field where the combine is operating. This necessary practice almost always creates an elevational difference between the two vehicles. These road trucks themselves also have widely varying heights. These two conditions create a big variation in the optimum elevation of the discharge point of the combine unloading system. Combine manufacturers have attempted to address this problem with ever longer augers and higher fixed swing out arcs. There are, however, limits to both. This fixed point discharge point frequently ends up too high, too low, too far from the combine, or too close to the combine for optimum truck loading conditions. Such conditions require repositioning the while combine with respect to the vehicle it is loading.
Existing combine unloading systems can unload from one side of the machine only. This frequently requires 180.degree. turns by the combine to position it on the proper side to unload the grain into the road truck. It also means that the combine can be unloaded into a moving grain cart when traveling only in one direction through the field since access to one side of the combine is virtually always blocked by unharvested crop.
When topping off or completely filling the truck or wagon, it is necessary for the operator to inch the combine forward or backward during the process. In addition to being cumbersome, the combine must be positioned close to perfectly parallel to the receiving vehicle or a stop and reposition is necessary. The lack of parallelism frequently cannot be solved by moving the auger through its fixed arc.
An agricultural combine has multiple steering requirements. Precise control is needed as the row harvesting units such as a cornhead, are guided through the rows of grain. When the end of the field is reached, a tight turning radius is needed to proceed back across the field in order to harvest the crop immediately adjacent to the just-completed rows or round. Concomitant with its field performance, this large vehicle also must be controlled on the roadway at speeds of around 20 mph and around tight corners. Another steering associated problem is to turn multiple axle, heavily-loaded bogies with large tires in a tight radius while minimizing sliding the tires in the horizontal direction which places high stresses in the suspension, piles up dirt in the field, and causes excessive tire wear.
An early attempt at an articulated combine is reported in U.S. Pat. No. 4,317,326. The design capacity is stated to be around 360 bushels. Its unloading mechanism is limited to one side of the combine and steering is accomplished only by articulation steering cylinders. To date, no articulated combine is commercial. Clearly, there is a need for a more flexible, faster, and convenient combine which overcomes these and other problems such as those set forth above.